Freja SWAZI

Satellite Warning of Auroral Zone Increases (SWAZI)

Estimated Ionospheric Current Patterns

Expansions of the auroral oval in the northern hemisphere can be detected from space by the Freja spacecraft in low earth orbit. Increased field-aligned current activity, indicated by magnetic field fluctuations in the 1.5-50 Hz range, are used to trigger the Freja Magnetic Field Experiment's burst mode and to automatically generate these SWAZI reports. From the time interval during which the spacecraft track intersects the expanded oval, an estimated ionospheric current pattern based on the statistical Iijima-Potemra field-aligned pattern has been determined. These patterns are shown here, with the sun always being to the left (Noon Magnetic Local Time appears as a break in the outer pattern).

We have employed this technique post facto to analyze events from both the UARS and Freja missions. A collection of such FAC images are achived here for subsequent study.

The algorithm used for this process is available.

This prototype monitoring system officially ceased operations effective 18 July 1995.

Prepared and Maintained by J.B. Gary, jim.gary@jhuapl.edu
 
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Contact: Shin Ohtani